Algemeen

The traditional approach to toxicity testing is to consider dose (concentration)-effect relationships at arbitrarily fixed exposure durations which are supposed to reflect ‘acute’ or ‘chronic’ time scales. This approach measures the proportion of all exposed individuals responding by the end of different exposure times. Toxicological databases established in this way are collections of endpoint values obtained at fixed times of exposure. As such these values cannot be linked to make predictions for the wide range of exposures encountered by humans or in the environment. Thus, current toxicological risk assessment can be compromised by this approach to toxicity testing, as will be demonstrated in this paper, leading to serious underestimates of actual risk. This includes neonicotinoid insecticides and certain metallic compounds, which may require entirely new approaches. In order to overcome this handicap, an increasing number of researchers are using a variant of the traditional toxicity testing protocol which includes time to event (TTE) methods. This TTE approach measures the times to respond for all individuals, and provides information on the acquired doses as well as the exposure times needed for a toxic compound to produce any level of effect on the organisms tested. Consequently, extrapolations and predictions of toxic effects for any combination of concentration and time are now made possible.

The future of Australian birds is bleak, according to a new report called The Action Plan for Australian Birds 2010, which was carried out by researchers from Birds Australia (formerly the Royal Australasian Ornithologists Union), Charles Darwin University in the Northern Territory and the national science agency CSIRO. It classifies every Australian species and subspecies of bird according to the International Union for Conservation of Nature's Red List guidelines, which is the international standard for measuring risk of extinction. Birds moving into the danger zone include the western ground parrot, the regent honeyeater and orange-bellied parrot. The grey-headed albatross from Macquarie Island in the southwest corner of the Pacific Ocean is listed as 'critically endangered'. In total, 13% of bird species in Australia are under threat. The report applies current knowledge to change the conservation standing of 66 birds since the last action plan report in 2000. It lists 27 as extinct, 20 as critically endangered, 68 as vulnerable and 63 as near threatened.

2010 veröffentlichte der holländische Toxikologe Henk Tennekes ein international beachtetes Fachbuch mit dem Titel »Disaster in the Making«. Er beschreibt das extreme Artensterben bei Insekten und Vögeln der Agrarlandschaft – in England genauso wie in Holland oder Deutschland. Rebhühner, Kiebitze, Haubenlerchen und Braunkehlchen und selbst die früher so häufige Feldlerche werden immer seltener. Tennekes belegt das Artensterben mit vielen wissenschaftlichen Publikationen, die er in seinem Buch vorstellt. Die Ursache sieht der Toxikologe in einer Gruppe neuer Pestizide, der Neonikotinoide. Diese fordert er sofort zu verbieten. Noch vor Weihnachten 2011 kam die limitierte deutsche Ausgabe mit dem Titel »Das Ende der Artenvielfalt – Neuartige Pestizide töten Insekten und Vögel« auf den Markt.

The list of threatened birds, a testimony to human culpability, exploitation and neglect, is increasing every year. Just to take India’s case there were seven critically endangered species in 2000. Their numbers went up to nine in 2001; they increased to 12 in 2008; 14 in 2010 and 15 in 2011, when the Great Indian Bustard Ardeotis nigriceps was added to the list. According to IUCN, critically endangered species are those facing extremely high risk of extinction in the wild in the immediate future, and if nothing is done, the species might become extinct in 10 years, or in less than three generations (see http://iucn.org/themes/ssc/siteindex.htm for more details). Marginally less threatened, according to the IUCN criterion, are endangered species. There are 16 endangered bird species in India, including Lesser Florican Sypheotides indicus, Egyptian Vulture Neophron percnopterus, Narcondam Hornbill Rhyticeros narcondami and Masked Finfoot Heliopais personata. Then there are vulnerable species: these face high risk of extinction in the wild in the medium term. Fifty-eight Indian birds fall in this category. The species that are at a lower risk are termed near threatened. These are species I consider “sick”. They are not likely to die soon, but need our care and support to survive. There are 68 such species in India based on existing information but a comprehensive assessment of Indian birds is quite likely to make the list longer.